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Dynamic antagonism between ETR-3 and PTB regulates cell type-specific alternative splicing
Nicolas Charlet-B1, Penny Logan, Gopal Singh
1Department of Pathology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Molecular Cell
|April 5, 2002
Summary
Cell-specific gene splicing is regulated by competing proteins. ETR-3 (a CELF family member) activates cardiac troponin T (cTNT) exon 5 inclusion, while PTB represses it, demonstrating active cellular regulation.
Area of Science:
- Molecular Biology
- RNA Splicing
- Gene Regulation
Background:
- Alternative splicing generates protein diversity.
- Cardiac troponin T (cTNT) exon 5 inclusion is critical for embryonic muscle development.
- Splicing regulation involves intronic splicing elements and RNA-binding proteins.
Purpose of the Study:
- To investigate the regulatory mechanisms controlling cTNT exon 5 splicing.
- To identify the roles of ETR-3 and polypyrimidine tract binding protein (PTB) in this process.
- To demonstrate antagonistic splicing activities within cells.
Main Methods:
- In vitro binding assays to study protein-RNA interactions.
- Expression of dominant-negative mutants to assess protein function in vivo.
- Analysis of MSE-dependent splicing activation and repression in muscle and nonmuscle cells.
Main Results:
- ETR-3 binds U/G motifs in MSEs and activates cTNT exon 5 inclusion.
- PTB antagonizes ETR-3 binding and represses exon inclusion.
- Endogenous CELF and PTB activities are essential for cell-specific splicing.
- Antagonistic splicing activities were demonstrated in vivo within the same cells.
Conclusions:
- Cell-specific splicing regulation arises from the dominance of competing regulatory states.
- ETR-3 and PTB act antagonistically to control cTNT exon 5 splicing.
- This study provides in vivo evidence for competing splicing regulatory factors within cells.